jade.core.behaviours
Class FSMBehaviour

java.lang.Object
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  +--jade.core.behaviours.Behaviour
        |
        +--jade.core.behaviours.CompositeBehaviour
              |
              +--jade.core.behaviours.FSMBehaviour

Direct Known Subclasses:

AchieveREInitiator, AchieveREResponder

public class FSMBehaviour

extends CompositeBehaviour

Composite behaviour with Finite State Machine based children scheduling. It is a CompositeBehaviour that executes its children behaviours according to a FSM defined by the user. More specifically each child represents a state in the FSM. The class provides methods to register states (sub-behaviours) and transitions that defines how sub-behaviours will be scheduled.

At a minimum, the following steps are needed in order to properly define a FSMBehaviour:

• register a single Behaviour as the initial state of the FSM by calling the method registerFirstState;
• register one or more Behaviours as the final states of the FSM by calling the method registerLastState;
• register one or more Behaviours as the intermediate states of the FSM by calling the method registerState;
• for each state of the FSM, register the transitions to the other states by calling the method registerTransition;
• the method registerDefaultTransition is also useful in order to register a default transition from a state to another state independently on the termination event of the source state.

A number of other methods are available in this class for generic tasks, such as getting the current state or the name of a state, ...

Author:

Giovanni Caire - CSELT

See Also:

SequentialBehaviour, ParallelBehaviour, Serialized Form

Inner classes inherited from class jade.core.behaviours.Behaviour

Behaviour.RunnableChangedEvent

Fields inherited from class jade.core.behaviours.CompositeBehaviour

currentExecuted

Fields inherited from class jade.core.behaviours.Behaviour

myAgent, myEvent, NOTIFY_DOWN, NOTIFY_UP, parent

Constructor Summary

FSMBehaviour()
Default constructor, does not set the owner agent.

FSMBehaviour(Agent a)
This constructor sets the owner agent.

Method Summary

protected boolean	checkTermination(boolean currentDone, int currentResult) Check whether this FSMBehaviour must terminate.
protected Collection	getChildren() Return a Collection view of the children of this SequentialBehaviour
protected Behaviour	getCurrent() Get the current child
int	getLastExitValue()
java.lang.String	getName(Behaviour state)
Behaviour	getState(java.lang.String name)
protected void	handle(Behaviour.RunnableChangedEvent rce) Handle block/restart notifications.
int	onEnd() Override the onEnd() method to return the exit value of the last executed state.
void	registerDefaultTransition(java.lang.String s1, java.lang.String s2) Register a default transition in the FSM defining the policy for children scheduling of this FSMBehaviour.
void	registerFirstState(Behaviour state, java.lang.String name) Register a Behaviour as the initial state of this FSMBehaviour.
void	registerLastState(Behaviour state, java.lang.String name) Register a Behaviour as a final state of this FSMBehaviour.
void	registerState(Behaviour state, java.lang.String name) Register a Behaviour as a state of this FSMBehaviour.
void	registerTransition(java.lang.String s1, java.lang.String s2, int event) Register a transition in the FSM defining the policy for children scheduling of this FSMBehaviour.
protected void	scheduleFirst() Prepare the first child for execution.
protected void	scheduleNext(boolean currentDone, int currentResult) This method schedules the next child to be executed.

Methods inherited from class jade.core.behaviours.CompositeBehaviour

action, block, done, onStart, postAction, preAction, reset, restart

Methods inherited from class jade.core.behaviours.Behaviour

actionWrapper, block, getDataStore, isRunnable, root, setAgent, setDataStore

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

FSMBehaviour

public FSMBehaviour()

Default constructor, does not set the owner agent.

FSMBehaviour

public FSMBehaviour(Agent a)

This constructor sets the owner agent.

Parameters:

a - The agent this behaviour belongs to.

Method Detail

registerState

public void registerState(Behaviour state,
                          java.lang.String name)

Register a Behaviour as a state of this FSMBehaviour. When the FSM reaches this state the registered Behaviour will be executed.

Parameters:

state - The Behaviour representing the state

name - The name identifying the state.

registerFirstState

public void registerFirstState(Behaviour state,
                               java.lang.String name)

Register a Behaviour as the initial state of this FSMBehaviour.

Parameters:

state - The Behaviour representing the state

name - The name identifying the state.

registerLastState

public void registerLastState(Behaviour state,
                              java.lang.String name)

Register a Behaviour as a final state of this FSMBehaviour. When the FSM reaches this state the registered Behaviour will be executed and, when completed, the FSMBehaviour will terminate too.

Parameters:

state - The Behaviour representing the state

name - The name identifying the state.

registerTransition

public void registerTransition(java.lang.String s1,
                               java.lang.String s2,
                               int event)

Register a transition in the FSM defining the policy for children scheduling of this FSMBehaviour.

Parameters:

s1 - The name of the state this transition starts from

s2 - The name of the state this transition leads to

event - The termination event that fires this transition as returned by the onEnd() method of the Behaviour representing state s1.

See Also:

Behaviour.onEnd()

registerDefaultTransition

public void registerDefaultTransition(java.lang.String s1,
                                      java.lang.String s2)

Register a default transition in the FSM defining the policy for children scheduling of this FSMBehaviour. This transition will be fired when state s1 terminates with an event that is not explicitly associated to any transition.

Parameters:

s1 - The name of the state this transition starts from

s2 - The name of the state this transition leads to

getState

public Behaviour getState(java.lang.String name)

Returns:

the Behaviour representing the state whose name is name.

getName

public java.lang.String getName(Behaviour state)

Returns:

the name of the state represented by Behaviour state.

getLastExitValue

public int getLastExitValue()

Returns:

the exit value of the last executed state.

onEnd

public int onEnd()

Override the onEnd() method to return the exit value of the last executed state.

Overrides:

onEnd in class CompositeBehaviour

Tags copied from class: CompositeBehaviour

See Also:

Behaviour.onEnd()

scheduleFirst

protected void scheduleFirst()

Prepare the first child for execution. The first child is the Behaviour registered as the first state of this FSMBehaviour

Overrides:

scheduleFirst in class CompositeBehaviour

See Also:

CompositeBehaviour.scheduleFirst()

scheduleNext

protected void scheduleNext(boolean currentDone,
                            int currentResult)

This method schedules the next child to be executed. It checks whether the current child is completed and, in this case, fires a suitable transition (according to the termination event of the current child) and schedules the child representing the new state.

Overrides:

scheduleNext in class CompositeBehaviour

Parameters:

currentDone - a flag indicating whether the just executed child has completed or not.

currentResult - the termination value (as returned by onEnd()) of the just executed child in the case this child has completed (otherwise this parameter is meaningless)

See Also:

CompositeBehaviour.scheduleNext(boolean, int)

checkTermination

protected boolean checkTermination(boolean currentDone,
                                   int currentResult)

Check whether this FSMBehaviour must terminate.

Overrides:

checkTermination in class CompositeBehaviour

Returns:

true when the last child has terminated and it represents a final state. false otherwise

See Also:

CompositeBehaviour.checkTermination(boolean, int)

getCurrent

protected Behaviour getCurrent()

Get the current child

Overrides:

getCurrent in class CompositeBehaviour

See Also:

CompositeBehaviour.getCurrent()

getChildren

protected Collection getChildren()

Return a Collection view of the children of this SequentialBehaviour

Overrides:

getChildren in class CompositeBehaviour

See Also:

CompositeBehaviour.getChildren()

handle

protected void handle(Behaviour.RunnableChangedEvent rce)

Handle block/restart notifications. An FSMBehaviour is blocked only when its currently active child is blocked, and becomes ready again when its current child is ready. This method takes care of the various possibilities.

Overrides:

handle in class Behaviour

Parameters:

rce - The event to handle.